Thermal analysis relates to all the means making it possible to estimate the temperatures tolerated by a component, a piece of equipment or a structure of a vehicle. This estimation relies on an analysis of the laws of the physics thermal exchanges (phenomena of conduction, diffusion, convection, radiation, advection), and the representation thereof in mathematical form, making it possible to solve the heat equation. One of the means known for performing this estimation comprises solving mathematical models by digital means, relying on the finite differences, finite elements or finite volume methods.
The thermal models of the prior art intended to predict the temperature ranges for a component, a piece of equipment or a structure of a vehicle such as an airplane, for example, rely on a number of intrinsic properties of the vehicle such as its geometry, its materials, and the performance levels of its systems, and on extrinsic parameters such as climatic flows, number of passengers, operations specific to the airlines when the vehicles are airplanes, the external paint work, (the livery) of the airplane, the operational flight profile, the maintenance operations, the nature of the fuel, the quantities of flights, etc. These thermal models are either nodal models relying on the finite differences method, or models relying on the finite elements or even finite volumes technique. These thermal models rely also on standardized extrinsic parameters which depend on the climatic conditions, the standard airplane operations, or even standardized flight profiles. The extrinsic parameters which are introduced into the model are defined so as to cover the possible range of climatic environments, the possible range of operations on the vehicle, possible liveries, from very light to very dark, typical flight profiles (for example, short haul, medium haul, long-haul mission, etc.), and the number of passengers in as much as a number of scenarios can be considered according to the load factor. Thus, for example, the climatic environment range must cover all the conditions which could be encountered at all the world airports frequented by the vehicle, and all the seasons, from extreme cold to extreme heat, and do so for all the altitudes at which the airplane could fly.
For the extreme hot and cold cases, standards have been defined on the basis of documents describing the extreme climatic conditions such as, for example, military standards documents, or even environmental climatic standards. These standards describe the climatology of the extreme day considered (air temperature, winds, solar radiations). For the liveries of the airlines, theoretical levels are considered which take into consideration the fact that dark colors absorb heat more than light colors. Ultimately, the temperatures thus estimated on the components, pieces of equipment or structures of a vehicle are assumed to be limited cases, and their probability of being exceeded is extremely rare because it depends on a stacking up of critical considerations, of paintwork, climate and operations.
Regarding the analyses of the life time of the components, pieces of equipment or structures of a vehicle, the prior art techniques rely also on a mixture of standardized cases including a certain percentage of tropical or polar flights, or flights in a standard atmosphere, with a paintwork of a given color. Here again the probability of actually obtaining this combination is not determined, the margins are not therefore known.
Another drawback with these techniques stems from the fact that the real conditions of use of the vehicles are such that the theoretically computed levels are far from being reached. Also, the methods for the prior art do not make it possible to know the probability of reaching these temperatures, and therefore of defining the margins in relation to the reality of the operations.
The invention aims to mitigate the drawbacks of the prior art described above by means of an analysis method based on real measurements of the flight conditions of an airplane on real climatic data measuring during the flights.